It is common practice to employ any device for keeping constant engine speed irrespective of the load the engine carries. The simplest device is a flywheel. However, it is not suitable for adjusting the fuel supply to the engine to counterbalance a disequilibrium between the generated power and the consumed power. To conduct an effective counterbalance, a governor has been devised. There are many types of governors, and a typical example is a centrifugal governor. The present invention is directed toward improvements upon a centrifugal governor, especially used for the horizontal diesel engines.
Referring to FIG. 7(A), which diagrammatically illustrates the internal construction of a conventional centrifugal governor, particularly an arrangement of levers 3, 31, 32, and 33. The illustrated centrifugal governor is a water-cooled system. An idling spring 5 is coupled to a governor lever 3 such that it can be spring-biased to cover a full range from the non-load (0/4) up to the full-road (4/4). This will become clearer from the graph of FIG. 7(B), which indicates variations in the tensile force of the idling spring. More specifically, the idling spring 5 is spring-biased to shift the governor lever 3 to increase the supply of fuel (in the R direction); that is, from the non-load set (0/4) to the full-load set (4/4).
However, the conventional centrifugal governor has the following disadvantage:
In a low-load set (LL) the governor can maintain a constant running speed, and in a high-load set (LH) it can minimize variations in the rated running speed of the engine, and increase its rising speed as a load increases. However, these two advantageous functions cannot be obtained at the same time, but they are in the relationship of “one or the other”.
More specifically, as indicated in FIG. 7(B), to ensure a constant running speed of the engine in the low-load set (LL) the idling spring 5 must be adjusted to a required tensile force variation rate θ 1. The tensile force (ISI) of the idling spring 5 varies from the non-load set (0/4) to the full-load set (4/4), wherein the variation rate is depicted in a diagonally upward straight line as shown in FIG. 7B. As a result, the tensile force variation width (ISF1) tends to have a large value in contrast to the tensile force variation rate θ 1.
By referring to FIG. 5(B), a state of equibrium will be described, wherein the state of equibrium is shown in dotted line drawn between the synthesized tensile force (STF1) of the tensile force (IS1) of the idling spring 5 and the tensile force (GS1) of the main spring 4 is depicted in a diagonally upward straight line. As shown in FIG. 5(C), the governor force (GF) of the governor weight 6 is brought into equilibrium with the running speed (rpm) of the engine. As a result, as shown in dotted line in FIG. 5D, the governor characteristics for controlling the running speed against a load becomes linear. Because of this linear continuous state of equilibrium, the conventional centrifugal governor can neither minimize the variation rate of the rated running speed in the high-load set (LH) nor increase the rising speed when a load increases.
Therefore, an object of the present invention is to improve the conventional centrifugal governor, and is to provide a centrifugal governor that can maintain a constant running speed in the low-load set (LL), and can minimize the variation rate of the rated running speed in the high-load set (LH), and also can increase its rising speed when a load is stepped up, wherein these two advantageous functions can be equally achieved, not one or the other like the conventional centrifugal governors.
Another object of the present invention is to provide a centrifugal governor having a simplified and durable structure under which the above-mentioned double advantageous functions are equally achieved.
A further object of the present invention is to provide a centrifugal governor which, not only in the low-load set (LL) but also in the middle high-load set (LMH), the above-mentioned advantageous functions are equally achieved, not one or the other like the conventional centrifugal governors.
A still further object of the present invention is to provide a centrifugal governor whose idling spring operates with the minimum loss of its tensile force by simplifying the mechanical integration in the joint of the idling spring to the governor lever.